It is common today for game players, or gamers, to participate in competitive play of video games, sometimes referred to as professional gaming, e-sport, and cybersport. Games are played competitively at amateur, semi-professional and professional levels, with some games having organized competitions in the form of leagues and tournaments. Some common video game genres associated with competitive play of video games include real-time strategy, fighting, first-person shooter, massively-multiplayer online, racing and multiplayer online battle arena
Some gaming services can provide multiplayer online services, such as chatting and game listings. It is not uncommon for such gaming services to have large numbers, e.g., tens or even hundreds of thousands of players logged on at any given time. Some gaming services can be incorporated into the electronic games that make use of them. Others can be provided through external interfaces used by other online services. Some examples of online gaming services include Xbox Live, Battle.net, Half-Life TV (hltv.org), Electronic Sports League—Europe (ESL.eu), and quakelive.com.
At least some of these services include a matchmaking concept, sometimes referred to as arranged teams. In an arranged team game, such as Battle.net's Warcraft III, a player can form a team with one or more other players. The team, once formed, can be anonymously matched up with another team of similar size and rank. Matchmaking techniques can use a ranking algorithm, such as a Bayesian ranking algorithm developed by Microsoft Research and used in the Xbox® matchmaking system. Other systems rely on a player's rating dependent upon an outcome of games, e.g., wins and/or losses, between rated players.